Why does the earth's rotation slow down spring and speed up autumn?

It takes the same time for the earth to make one revolution. You should ask why summer is longer than spring. Because the earth is tilted, the direct point of the sun will change within a year. In spring and autumn, the sun shines directly on the equator, and the length of day and night is equal. In summer, when the direct point of the sun moves northward to the northern hemisphere, the days in our northern hemisphere are longer than the nights. In winter, the direct point of the sun is in the southern hemisphere, so the days in the southern hemisphere are longer than the nights. At this time, the days in our northern hemisphere are shorter than the nights. So the length of day and night varies throughout the year, but it is 24 hours a day. This is a question of the length of day and night.

Among the 24 solar terms, we have four solar terms: vernal equinox, summer solstice, autumn equinox and winter solstice. At the vernal equinox and the autumnal equinox, the sun shines directly on the equator, so our days and nights are equal in length. After the vernal equinox, we came to the summer solstice. In the northern hemisphere, we have longer days and shorter nights.

During the summer solstice, the northern hemisphere has the longest day and the shortest night. During the summer solstice and autumnal equinox, as the direct point of the sun moves south, day and night begin to change in opposite directions. However, during this period, there are still long days and short nights in the northern hemisphere. In the autumnal equinox, the sun shines directly on the equator, and the length of day and night is equal all over the world. Since then, the direct point of the sun has been moving towards the southern hemisphere. Therefore, in the northern hemisphere, the period of short days and long nights began. At this time, the southern hemisphere is characterized by long days and short nights.

Seeing this, I think you should understand that the length of our day and night is not caused by the rotation speed of the earth, but by the point where the sun shines directly on the earth. The equatorial plane of our earth forms an angle with the ecliptic rotation plane of the ecliptic angle. In other words, our earth is tilted when it rotates around the sun. After the sunlight is irradiated, the illumination span is different at different latitudes and longitudes, and the rotation angular velocity is the same, which leads to different lengths of day and night at different latitudes.